Cognito Login Authentication via Lambda

gistfile1.txt

//When stackoverflow can't help you...

const AWS = require('aws-sdk');
var AmazonCognitoIdentity = require('amazon-cognito-identity-js');
var CognitoUserPool = AmazonCognitoIdentity.CognitoUserPool;
var AuthenticationDetails = AmazonCognitoIdentity.AuthenticationDetails;
var CognitoUser = AmazonCognitoIdentity.CognitoUser;

exports.handler = (event, context, callback) => {

  
    let user_name = 'youremail@email.com'
    let pass_word = 'user password'
    let user_pool_id = 'ap-southeast-x-xxxxx'
    let user_pool_client_id = '3oro9erh'
    let federated_identity_id = 'ap-southeast-1:46ffe098-cb9b-xxxxx'
    

        var poolData = {
            UserPoolId: user_pool_id,
            ClientId:  user_pool_client_id
        };
        var userPool = new CognitoUserPool(poolData);

        AWS.config.region = 'ap-southeast-1';
        AWS.config.credentials = new AWS.CognitoIdentityCredentials({
            IdentityPoolId: federated_identity,
        });

        var authenticationData = {
            Username: user_name,
            Password: pass_word
        };
        var authenticationDetails = new AuthenticationDetails(authenticationData);

        var userData = {
            Username: user_name,
            Pool: userPool
        };

        var cognitoUser = new CognitoUser(userData);

        cognitoUser.authenticateUser(authenticationDetails, {
            onSuccess: function (result) {
              console.log('access token + ' + result.getAccessToken().getJwtToken());
              
            },

            onFailure: function (err) {
              console.log('Login error: ' + err);
              
            }
        });
        
}        

This helped me.
I was missing the AWS.config.region and AWS.config.credentials.
However, I didn't add the AWS.config.credentials though.

Thank you.